Question: $ { \left[\begin{array}{rr}{-1} & {2} \\ {0} & {-1}\end{array}\right]-\left[\begin{array}{rr}{-1} & {-2} \\ {-2} & {1}\end{array}\right] = {?} } $
Explanation: To find the difference of two matrices, subtract the corresponding items between each matrix. ${\left[\begin{array}{rr}{-1}-{-1} & {2}-{-2} \\ {0}-{-2} & {-1}-{1}\end{array}\right]}$ Now, simplify: ${\left[\begin{array}{rr}{0} & {4} \\ {2} & {-2}\end{array}\right]}$